1. Field
The present invention relates to an accelerator pedal device that is applicable to vehicles and the like adopting the drive-by-wire system, and in particular relates to an accelerator pedal device including an active control mechanism that generates, for danger avoidance or danger warning, reactive force (that is, push back force) that counteracts the pedal force of the pedal arm.
2. Description of the Related Art
As an accelerator pedal device that is applicable to a computerized throttle system (drive-by-wire system) in an engine mounted on a vehicle or the like, known is a type including a pedal arm that is formed integrally with an accelerator pedal and swingably supported by a housing, a return spring for returning the pedal arm to a rest position, a hysteresis generation mechanism for generating hysteresis in the pedal load (pedal force), a position sensing device for detecting the angular position of the pedal arm, and so on, and which uses the position sensing device to detect the applied amount (angular position) of the accelerator pedal (pedal arm), and controls the output of the engine based on the detection signal (for instance, refer to Japanese Patent Laid-Open Publication No. 2004-155375).
Meanwhile, with vehicles in recent years, accelerator pedal devices including an active control mechanism are being developed for performing control so as to push back the accelerator pedal by going against the flooring operation of the driver when the vehicle ahead comes near while driving or when it is necessary to warn or notify other dangers.
As this kind of accelerator pedal device, known is a type including a pedal arm that is formed integrally with the accelerator pedal and supported swingably by a housing (case bracket), a spindle that is supported swingably by the pedal arm, and a coil-shaped return spring for returning the pedal arm to the rest position, and further including an active control mechanism (accelerator restraining means) including a rod capable of coming in contact with an upper end of the pedal arm that is disposed so as to pass through the return spring, a slider for retaining a rod and a second spring for biasing the rod toward the pedal arm side, a lead screw that is rotatably supported by the housing so as to reciprocally drive the slider and integrally formed with the gear, and a motor that is fixed to the house so as to rotatably drive the worm gear that engages with the gear of the lead screw (for instance, refer to Japanese Patent Laid-Open Publication No. 2007-137152).
Nevertheless, since this kind of active control mechanism adopts a pathway of the driving force (push back force) of worm gear, gear and lead screw, and then slider and rod, the structure becomes complex and the device becomes a large size, and this is undesirable because the responsiveness will be inferior (response speed will be slow) when danger avoidance or the like is required.
Moreover, while the pedal arm swings (rotates) around the spindle, the rod of the accelerator control mechanism reciprocates linearly. Thus, since the upper end of the pedal arm describes an arc while the apical part of the rod describes a linear trajectory, the contact status upon the apical part of the rod coming in contact with the upper end of the pedal arm will change according to the angle of the pedal arm, and there is a problem in that preferable restraining force (push back force) cannot be obtained.
Moreover, if the active control mechanism (accelerator restraining means) described in Japanese Patent Laid-Open Publication No. 2007-137152 is applied to the accelerator pedal device described in Japanese Patent Laid-Open Publication No. 2004-155375, since the accelerator pedal device of Japanese Patent Laid-Open Publication No. 2004-155375 is configured by including a hysteresis generation mechanism, the structure becomes even more complex and the application as-is will be difficult. If the hysteresis generation mechanism and the active control mechanism are combined, it is necessary to ensure the independence of the respective functions so that one mechanism does not affect the other mechanism.
Accordingly, the development of an accelerator pedal device having a simple structure and able to seek miniaturization, the hysteresis generation mechanism and the active control mechanism, which are able to function reliably in an independent manner, and capable of active control superior in responsiveness, is needed.